Microsurgical Fenestration of Middle Fossa Arachnoid Cyst in a Pediatric Patient Through a Keyhole Approach with Endoscopic Inspection. 2-Dimensional Operative Video

In recent decades, the management of middle fossa arachnoid cysts in pediatric patients has evolved significantly through the integration of novel techniques, such as the utilization of endoscopy systems1 and implementation of minimally invasive approaches like keyhole craniotomy.2,3 These cystic formations, occurring within the arachnoid membrane, may lead to neurologic impairments and raised intracranial pressure if left untreated.4 The utilization of endoscopy to aid microsurgical techniques or as a complement to them provides a level of visualization and manipulation of the cyst walls that is significantly more precise than the isolated use of a microscope.1 The keyhole craniotomy allows for reduced surgical trauma, smaller incisions, and quicker recovery times.5 In Video 1, we present the case of a 2-year-old patient with bilateral middle fossa arachnoid cysts exerting mass effect on the adjacent parenchyma. The patient was referred to our institution due to developmental delay and cognitive issues related to language and social interactions. On the basis of imaging findings and clinical correlation, we opted for a microsurgical fenestration with endoscopic inspection using a keyhole craniotomy to minimize complications and enhance the benefits of both techniques. Throughout the surgical video, tricks and considerations that contribute to the combined procedure's efficiency and ease of execution are highlighted and discussed. Postoperative images showed no complications, and the patient was discharged 3 days after surgery.

Intracranial Epidermoid Cyst: A Volumetric Study of a Surgically Challenging Benign Lesion

BACKGROUND

Intracranial epidermoid cysts are rare, benign tumors. Nevertheless, the microsurgical removal of these cysts is challenging. This is due to their capacity to adhere to the neurovascular tissue, as well as the associated difficulties in microsurgically peeling off their capsular wall hidden in dead angles. To better understand the rate of recurrence after surgical intervention, we have performed preoperative and postoperative volumetric analysis of epidermoid cysts, allowing the estimation of their growth rate after resection.

METHODS

Imaging data from 22 patients diagnosed and surgically treated for an intracranial epidermoid cyst between 2000 and 2022 were retrospectively collected from 2 European neurosurgical centers with microsurgical expertise. Volumetric analysis was performed on magnetic resonance imaging data.

RESULTS

Average cyst volume at diagnosis, before any surgery, measured in 12 patients was 28,877.6 ± 10,250.4 mm3 (standard error of the mean [SEM]). Estimated growth rate of incompletely resected epidermoids after surgery was 1,630.05 mm3 ± 729.95 (SEM). Assuming linear growth dynamics and normalizing to postoperative residual volume, the average postoperative growth rate corresponded to 61.5% ± 34.3% (SEM) of the postoperative residual volume per year. We observed signs of recurrence during a radiologic follow-up period of 6.0 ± 2.8 years (standard deviation) in more than 50% of our patients.

CONCLUSIONS

Due to their slow-growing nature, epidermoid cysts can often reach a complex multicompartmental size before resection, even in young patients, thus requiring complex approaches with challenging capsular resection, which implies a high risk of nerve and vascular injury per se. Tumor recurrence may be predicted on the basis of postoperative volumetry.

Unruptured Brain Arteriovenous Malformations: A Systematic Review and Meta-Analysis of Mortality and Morbidity in Aruba-Eligible Studies

BACKGROUND

Treating unruptured brain arteriovenous malformations (bAVMs) represent significant challenges, with numerous uncertainties still in debate. The ARUBA trial induced further investigation into optimal management strategies for these lesions. Here, we present a systematic-review and meta-analysis focusing on ARUBA-eligible studies, aiming to correlate patient data with outcomes and discuss key aspects of these studies.

METHODS

Following PRISMA guidelines, we conducted a systematic-review. Variables analyzed included bAVM Spetzler-Martin (SM) grade, treatment modalities, and outcomes such as mortality and neurological deficits. We compared studies with a minimum of 50% cases classified as SM 1-2 lesions and those with less than 50% in this category. Similarly, a comparison between studies with at least 50% microsurgery-cases and those with less than 50% was performed. We examined correlations between mortality incidence, SM distribution, and treatment modalities.

RESULTS

Our analysis included 16 studies with 2.417 patients. The frequency of bAVMs SM-grade 1-2 ranged from 44% to 76%, SM-grade 3 from 19% to 48%, and SM 4-5 from 5 to 23%. Notably, studies with more than 50% cases presenting lesions SM-grade 1-2 presented significantly lower mortality rates than those with less than 50% cases of SM 1-2 lesions (P < 0.001). No significant difference in mortality rates or neurological deficits was identified between studies with more than 50% of microsurgery-cases and those with less than 50%.

CONCLUSIONS

The analysis revealed that studies with a higher proportion of bAVMs presenting SM 1-2 lesions were associated with lower mortality rates. Mortality did not show a significant association with treatment modalities.

Trascallosal bilateral transforaminal resection of a solid partially calcified colloid cyst: 2D operative video

BACKGROUND

Colloid cysts are benign lesions of the roof of the third ventricle, often diagnosed incidentally; sometimes they can cause hydrocephalus due to obstruction of the foramina of Monroe. Symptomatic cysts could be resected either microsurgically (transcallosal or transcortical) or endoscopically. Although both strategies are effective and have advantages and disadvantages, there is no consensus on the choice of the optimal approach. Transcallosal resection, although more invasive than endoscopy, allows adequate bimanual manipulation of the cyst and is associated with high rates of complete resection, the use of neuronavigator and intraoperative ultrasound optimizes surgical trajectory and improves safety of the procedure with complication rates comparable to endoscopy. Endoscopy is less invasive but complete resection of solid cysts can be challenging.

CASE DESCRIPTION

In Video 1, we show resection of a solid partially calcified colloid cyst using a transcallosal bilateral transforaminal approach to anterior third ventricle male, 65 years old; headache and mild memory impairment for 6 months; admitted at our emergency department because of a brief loss of consciousness. Neurologic examination was normal. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a colloid cyst at the level of anterior third of the third ventricle (1.5 cm in diameter) with hypointense appearance in T2 sequences suggesting a solid calcific component. The ventricular system was enlarged. Colloid cyst risk score 3/5 (diameter >0.7 cm, headache, risk zone I) considered an intermediate-risk subgroup according to Alford et al. On this basis, we proposed the surgical treatment. We chose a transcallosal microsurgical resection. The patient gave consent for the procedure. A preoperative planning with a computer-generated 3D model is performed to simulate the approach. Craniotomy, interhemispheric dissection, and callosotomy were planned with the neuronavigator and with the aid of intraoperative ultrasound to optimize the trajectory and perform a limited and tailored callosotomy. The 1.5 cm callosotomy allows to approach both lateral ventricles, the cyst was progressively dissected working bilaterally through both foramina of Monroe without injuries of the fornices. Resection at term is complete. Postoperative MRI and CT scan confirmed complete excision without complications; the patient was discharged after a week in good neurological condition with complete regression of headache.

CONCLUSION

Microscopic transcallosal resection of the colloid cyst of the third ventricle allows for complete resection with low complication rates. The use of preoperative 3D planning and integrated neuronavigation with intraoperative ultrasound helps to reduce invasiveness.

Application of Tinel's test combed with clinical neurosensory test distinguishes spontaneous healing of lingual nerve neuropathy after mandibular third molar extraction

BACKGROUND

Extraction of the mandibular third molar, the most frequent and important surgical procedure in the clinical practice of oral surgery, is associated with the risk of injury of the lingual nerve. Neuropathy of the lingual nerve poses diagnostic challenges regarding the transient or permanent nature of the injury. No consensus or criteria have been established regarding the diagnosis of lingual nerve neuropathy. We applied both Tinel's test and clinical neurosensory testing together, which can be easily used at the bedside in the early stages of injury. Therefore, we propose a new method to differentiate between lesions with the ability to heal spontaneously and those that cannot heal without surgery.

RESULTS

Thirty-three patients (29 women,  4 men; mean age, 35.5 years) were included in this study. For all patients, the median interval between nerve injury and initial examination was 1.6 months and that between nerve injury and the second examination before determining the need for surgical management was 4.5 months. The patients were assigned to either group A or B. The spontaneous healing group (group A, n = 10) revealed a tendency for recovery within 6 months after tooth extraction. In this group, although there were individual differences in the degree of recovery, a remarkable tendency for recovery was observed based on clinical neurosensory testing in all cases. None of the patients were diagnosed with allodynia. In seven cases, the Tinel test result was negative at the first inspection, and in three cases, the result changed to negative at the second inspection. Conversely, in group B(n = 23), no recovery trend was observed with regard to clinical neurosensory testing, and nine patients had allodynia. Further, the Tinel test result was positive for all patients in both examinations.

CONCLUSIONS

Our findings indicate that in case of transient lingual nerve paralysis, clinical neurosensory testing findings deteriorate immediately after tooth extraction and gradually recover, while Tinel's test shows a negative result. Using Tinel's test and clinical neurosensory testing together enabled early and easy identification of the severity of the lingual nerve disorder and of lesions that would heal spontaneously without surgical management.

Suction cannula design for safe microneurosurgery

INTRODUCTION

Suction cannula (SC) is an important instrument for a neurosurgeon. Currently used suction control valves, kept in the sterile field, are controlled by the surgeon, for which he needs to leave the surgical dissection or by assistant or by operation room personnel to adjust the pressure of the equipment (suction machine or central suction), which lies in the unsterile field. Authors studied relationships of the different diameters of SC and the thumb hole (TH) of the SC and present their findings.

METHODS

Seven SC with various diameters of their lumen and TH were used for the study. Suction pressures were measured with suction tip open, immersed in saline and TH open and closed. TH of 2 SC were made smaller using adhesive tape over the TH and making smaller hole over the tape and two additional measurements were taken using changed SC with modified TH. SPSS Statistics 23.0 (IBM India Pvt Ltd, Bangaluru, India) was used for statistical analysis of the pressure recordings and SC features.

RESULTS

Pressure and diameter of ST or TH were related in opposite direction. As the diameter increases the pressure decreases. A strong negative association was observed between the diameter of TH and the pressure.

CONCLUSION

TH diameter of SC is important to control suction pressure with any size of SC. One should use tear-drop type TH or appropriate diameter of the circular type of TH to contemplate safe microneurosurgery.

Microneurosurgical Anatomic Study of the Horizontal Fissure of the Cerebellum

OBJECTIVE

The horizontal fissure of the cerebellum, which is the largest and most prominent fissure, has received less interest from anatomists and neurosurgeons. Hence, the current study aims to provide comprehensive detail about the horizontal fissure and its anatomic and surgical relationship with deeper structures such as the dentate nucleus and middle cerebellar peduncle for the benefit of the neurosurgeon.

METHODS

Ten whole formalin-fixed human cadaveric cerebellar hemispheres were obtained from human cadavers donated to the institution. Different parameters of the horizontal fissure were studied, such as length, depth (medial end, lateral end, and middle), sulcal and gyral variations (superficial and deep), and its close relationship, especially at depth, with the dentate nucleus and middle cerebellar peduncle.

RESULTS

The total length of the horizontal fissure on the right and the left side was 64.3 ± 7.9 mm (range, 53-77 mm) and 65.6 ± 8.01 mm (range, 53-79 mm), respectively. The medial third of the horizontal fissure, with the fewest vessels, was the most suitable place to puncture or start the dissection of the horizontal fissure. The surface projection of the center of the posterior border of the dentate nucleus lies within 20-21 mm on either side of the posterior midline along the horizontal fissure and is only approximately 4 mm deep from the horizontal fissure.

CONCLUSIONS

The anatomic measurements and relationships provided in this description of the horizontal fissure will serve as a tool for surgery selection and planning, as well as an aid to improve microneurosurgical techniques, with the final goal being better patient outcomes.

Endoscope-assisted microneurosurgery for intracranial aneurysms: A systematic review and meta-analysis

BACKGROUND

In the surgical approach to treat deep-seated intracranial lesions, endoscopes can be used to assist microsurgical operations and improve outcomes. This technique is often called endoscope-assisted microneurosurgery (EAM). This systematic review and meta-analysis aimed to evaluate the feasibility, safety, and effectiveness of EAM.

METHODS

We performed a meta-analysis of relevant articles identified using PubMed, Embase, and the Cochrane Central Register to assess the efficacy of EAM according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Primary outcomes were repositioning of the definitive clip, better surgical field, the overall and endoscope-related complication rates, mortality, and the rate of follow up.

RESULTS

A total of 10 studies of 1,432 patients with 1,717 aneurysms treated with EAM were included. EAM led to repositioning of the definitive clip in 13% (95% CI, 9%-17%; I₂ = 72.61%; p < 0.001); 77% of aneurysms treated with endoscopically assisted vision and information had a better outcome than that with standard surgery (95% CI, 52%-95%; I₂ = 97.63%; p < 0.001). There was an overall complication rate of 6% (95% CI, 1%-13%; I₂ = 91.39%; p < 0.001). The incidence of endoscope-related complications was 0% (95% CI, 0%-1%; I₂ = 64%; p < 0.001). The mortality was 0% (95% CI, 0-1%; I₂ = 0.0%); and 94% of patients had an excellent to good recovery and good outcome (95% CI, 88%-98%; I₂ = 88.42%; p < 0.001).

CONCLUSIONS

Our comprehensive study showed that EAM for intracranial aneurysms is feasible, the safety of the surgery is good, and the patients have a good prognosis, Therefore, we think EAM can be more widely adopted in the future.

Ischemic Stroke Revascularization

Extracranial-intracranial (EC-IC) bypass is one of the most fundamental techniques for ischemic cerebrovascular disease (CVD). We describe the standard surgical strategies, advanced techniques, and controversies concerning revascularization of ischemic stroke. The standard surgical strategies and techniques emphasize how to determine surgical indication, which should be decided for symptomatic internal carotid artery or middle cerebral artery (MCA) occlusive disease with misery perfusion detected by quantitative single photon emission computed tomography. Advanced techniques are available for complex situations such as posterior circulation revascularization, Bonnet bypass for common carotid artery obstruction, and various EC-IC bypasses for ischemia in the MCA and/or anterior cerebral artery territories using inter-grafts such as femoral veins and radial arteries, illustrated by our surgical results and experiences. Controversies include endovascular treatment complementary to EC-IC bypass. Finally, we advocate emergent EC-IC bypass for progressive ischemic CVD, particularly for contraindication or unsuccessful treatment after intravenous tissue plasminogen activator administration and/or endovascular thrombolysis. EC-IC bypass surgery can be reliable for ischemic CVD under strict optimal surgical indications using safe and reliable surgical techniques.

Microsurgical Treatment of Deep and Eloquent AVMs

Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.

Adoption of Advanced Microneurosurgical Technologies: An International Survey

BACKGROUND

Operating microscopes and adjunctive technologies are continually refined to advance microneurosurgical care. How frequently these advances are used is unknown. In the present study, we assessed the international adoption of microneurosurgical technologies and discussed their value.

METHODS

A 27-question electronic survey was distributed to cerebrovascular neurosurgeon members of U.S., European, and North American neurosurgical societies and social media networks of cerebrovascular and skull base neurosurgeons. The survey encompassed the surgeons' training background, surgical preferences, and standard microneurosurgical practices.

RESULTS

Of the respondents, 56% (53 of 95) were attendings, 74% (70 of 95) were in their first 10 years of practice, and 67% (63 of 94) practiced at an academic teaching hospital. Vascular, endovascular, and skull base fellowships had been completed by 38% (36 of 95), 27% (26 of 95), and 32% (30 of 95) of the respondents, respectively. Most respondents did not use an exoscope (78%; 73 of 94), a mouthpiece (61%; 58 of 95), or foot pedals (56%; 55 of 94). All 95 respondents used a microscope, and 71 (75%) used Zeiss microscopes. Overall, 57 neurosurgeons (60%) used indocyanine green for aneurysms (n = 54), arteriovenous malformations (n = 43), and dural arteriovenous fistulas (n = 42). Most (80%; 75 of 94) did not use fluorescence. The respondents with a vascular-focused practice more commonly used indocyanine green, Yellow 560 fluorescence, and intraoperative 2-dimensional digital subtraction angiography. The respondents with a skull base-focused practice more commonly used foot pedals and an endoscope-assist device.

CONCLUSIONS

The results from the present survey have characterized the current adoption of operative microscopes and adjunctive technologies in microneurosurgery. Despite numerous innovations to improve the symbiosis between neurosurgeon and microscope, their adoption has been underwhelming. Future advances are essential to improve surgical outcomes.

Evolution of microneurosurgical anatomy with special reference to the history of anatomy, surgical anatomy, and microsurgery: historical overview

This article reviews the evolution of microneurosurgical anatomy (MNA) with special reference to the development of anatomy, surgical anatomy, and microsurgery. Anatomy can be said to have started in the ancient Greek era with the work of Hippocrates, Galen, and others as part of the pursuit of natural science. In the sixteenth century, Vesalius made a great contribution in reviving Galenian knowledge while adding new knowledge of human anatomy. Also in the sixteenth century, Ambroise Paré can be said to have started modern surgery. As surgery developed, more detailed anatomical knowledge became necessary for treating complicated diseases. Many noted surgeons at the time were also anatomists eager to spread anatomical knowledge in order to enhance surgical practice. Thus, surgery and anatomy developed together, with advances in each benefiting the other. The concept of surgical anatomy evolved in the eighteenth century and became especially popular in the nineteenth century. In the twentieth century, microsurgery was introduced in various surgical fields, starting with Carl O. Nylen in otology. It flourished and became popularized in the second half of the century, especially in the field of neurosurgery, following Jacobson and Suarez's success in microvascular anastomosis in animals and subsequent clinical application as developed by M.G. Yasargil and others. Knowledge of surgical anatomy as seen under the operating microscope became important for surgeons to perform microneurosurgical procedures accurately and safely, which led to the fuller development of MNA as conducted by many neurosurgeons, among whom A.L. Rhoton, Jr. might be mentioned as representative.

Transcondylar Approach for Resection of Medullary Cavernous Malformation: 2-Dimensional Operative Video

Cavernous malformations located within the brainstem present with a high rate of neurological symptoms and carry a more aggressive course in both pediatric and adult populations.1,2 Cavernomas within the medulla are the rarest form, representing only 5% of all brainstem lesions.3 Repeated hemorrhage of brainstem cavernomas is associated with significant and cumulative neurological deficits and thus requires treatment.4 Microsurgical resection has become the optimal mode of treatment with the aim of resecting the live malformation and not merely the multiaged, organized hematoma.4 This is best achieved by approaching the cavernoma at the location where it projects to the surface and entering the lesion through a safe brainstem anatomic zone. For ventrally located lesions in the medulla, a transcondylar skull base approach provides a direct trajectory to the entry zone through a short surgical distance without the need to manipulate or retract neurovascular structures.5-8 Neuronavigation and intraoperative neurophysiological monitoring of somatosensory evoked potential, motor, and lower cranial nerves are adjuncts to increase patient safety. Radiosurgery for the treatment of brainstem cavernous malformations has been proposed; however, it demonstrates high risk and variable and often poor response rates.9 We present a surgical video demonstrating the transcondylar approach and resection of a medullary cavernoma in a 54-yr-old woman who has had multiple known prior hemorrhages and presented with a new onset of facial numbness and weakness, ataxia, and left body sensory loss. The patient consented to surgery and to photograph publication.  Images at 1:28, 1:43 (left), 2:02 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997,5 with permission.  Images at 1:43 (right) from Arnautovic et al,8 with permission from JNSPG.

The Resection of a Thalamic Pilocytic Astrocytoma Through the Transchoroidal Fissure, Transcallosal Approach: 2-Dimensional Operative Video

Surgical resection is the primary treatment of pilocytic astrocytomas and total removal can be curative. However, these lesions occur in critical areas, such as the thalamus, being surrounded by critical life neurovascular structures, which imposes a surgical challenge.1-5 Exhaustive acquisition and meticulous interpretation of preoperative radiological exams; reliable surgical orientation based on profound microneurosurgical anatomic knowledge and judicious discernment of the neuroanatomic distortions on the surface and deep-seated structures inflicted by the neuropathological entity; embracing and comprehensive application of the vast scope of available intraoperative guidance imaging and neurophysiological monitoring; in alliance with the mastered carefully microsurgical technique supported by endoscopic visualization are the keystones to the pursed duet "cure with quality of life" in the treatment of these lesions. We present the case of a 17-yr-old young lady with a progressive motor deficit in her right hemibody for over 2 yr. Her radiological investigation demonstrated a left thalamic lesion displacing the projection fibers (corticospinal tract) within the internal capsule laterally. The patient consented to the surgical procedure. The surgical strategy, intraoperative findings, and microsurgical and endoscopic technique, as well as the postoperative radiological and clinical evaluation are presented. The patient gave her informed consent for the publication of the case.

Koos grade IV vestibular schwannomas: considerations on a consecutive series of 60 cases-searching for the balance between preservation of function and maximal tumor removal

Koos grade IV vestibular schwannomas (VS) (maximum diameter > 3 cm) compress the brainstem and displace the fourth ventricle. Microsurgical resection with attention to the right balance between preservation of function and maximal tumor removal is the treatment of choice. Our series consists of 60 consecutive patients with unilateral VS, operated on from December 2010 to July 2019. All patients underwent microsurgical removal via the retrosigmoid approach. The adherence of VS' capsule to the surrounding nervous structures and the excessive tendency of tumor to bleed during debulking, because of a redundant vascular architecture, was evaluated by reviewing video records. Microsurgical removal of tumor was classified as total (T), near-total (NT: residue < 5%), subtotal (ST: residue 5-10%), or partial (P: residue > 10%). Maximal mean tumor diameter was 3,97 cm (SD ± 1,13; range 3,1-5,8 cm). Preoperative severely impaired hearing or deafness (AAO-HNS classes C-D) was present in 52 cases (86,7%). Total or NT resection was accomplished in 46 cases (76,7%), 65,8% in cases with, and 95,4% without tight adhesion of capsule to nervous structures (p < 0,001). Endoscopic-assisted microsurgical removal of VS in the IAC was performed in 23 patients: in these cases, a T resection was obtained in 78,3% versus 45,9% of microsurgery only (p < 0,001). The capsule of VS was tightly adherent to nervous structures in 63,3% of patients, whereas hypervascular high-bleeding tumors represented 56,7%. Hearing preservation was possible in 2 out of 8 patients with preoperative class B hearing. At last follow-up, 34 (56,7%) patients had a normal postoperative FN outcome (HBI), 9 (15,0%) were HBII, 8 (13,3%) HBIII, and 9 (15,0%) HBIV. The total NT resection of solid and low-bleeding VS, without tight capsule adhesion, was associated with better FN outcome. Mortality was zero; permanent complications were observed in 2 cases (diplopia, hydrocephalus), transient in 9. Microsurgery of Koos grade IV VS seems to be associated with more than acceptable functional results, with high rate of T and NT removal of tumor. Long-term FN results seem to be worse in patients with cystic Koos grade IV VS, in cases with tight capsule adherences to nervous structures and in high-bleeding tumors.

Open Fetal Microneurosurgery for Intrauterine Spina Bifida Repair

OBJECTIVES

The aim of the study was to describe the feasibility of open fetal microneurosurgery for intrauterine spina bifida (SB) repair and to compare perinatal outcomes with cases managed using the classic open fetal surgery technique.

METHODS

In this study, we selected a cohort of consecutive fetuses with isolated open SB referred to our fetal surgery center in Queretaro, Mexico, during a 3.5-year period (2016-2020). SB repair was performed by either classic open surgery (6- to 8-cm hysterotomy with leakage of amniotic fluid, which was replaced before uterine closure) or open microneurosurgery, which is a novel technique characterized by a 15- to 20-mm hysterotomy diameter, reduced fetal manipulation by fixing the fetal back, and maintenance of normal amniotic fluid and uterine volume during the whole surgery. Perinatal outcomes of cases operated with the classic open fetal surgery technique and open microneurosurgery were compared.

RESULTS

Intrauterine SB repair with a complete 3-layer correction was successfully performed in 60 cases either by classic open fetal surgery (n = 13) or open microneurosurgery (n = 47). No significant differences were observed in gestational age (GA) at fetal intervention (25.4 vs. 25.1 weeks, p = 0.38) or surgical times (107 vs. 120 min, p = 0.15) between both groups. The group with open microneurosurgery showed a significantly lower rate of oligohydramnios (0 vs. 15.4%, p = 0.01), preterm rupture of the membranes (19.0 vs. 53.8%, p = 0.01), higher GA at birth (35.1 vs. 32.7 weeks, p = 0.03), lower rate of preterm delivery <34 weeks (21.4 vs. 61.5%, p = 0.01), and lower rate of perinatal death (4.8 vs. 23.1%, p = 0.04) than the group with classic open surgery. During infant follow-up, the rate of hydrocephalus requiring ventriculoperitoneal shunting was similar between both groups (7.5 vs. 20%, p = 0.24). All patients showed an intact hysterotomy site at delivery.

CONCLUSION

Intrauterine spina repair by open fetal microneurosurgery is feasible and was associated with better perinatal outcomes than classic open fetal surgery.

Neurosurgical management of aneurysms of the vertebrobasilar system: increasing indications for endovascular therapy with a continued role for open microneurosurgery

Aneurysms of the vertebrobasilar system remain among the most challenging subsets of aneurysms to treat with an open surgical approach. Since Charles Drake's pioneering work in the 1960s, several advances in microsurgical techniques have improved outcomes and feasibility in the open surgical management of these aneurysms. In parallel, the field of endovascular neurosurgery has provided several safe and effective treatment options. Multiple trials have suggested that endovascular therapy for aneurysms of the vertebrobasilar system is superior to open surgical management in most cases. In some instances, however, open surgical management likely represents a more effective and durable option relative to endovascular therapy. Therefore, continued training of future cerebrovascular specialists in open surgery of vertebrobasilar aneurysms remains crucial. With widespread utilization of endovascular techniques, however, proper exposure of trainees to such aneurysms is growing increasingly difficult. In this review, we discuss the recent advances in the endovascular management of vertebrobasilar aneurysms while also emphasizing the continued importance of open microneurosurgery in such cases.

Redefining the Topography of the Tibial Nerve: Updated Treatment Guide for Tibial Nerve Entrapments: An Addendum to Surgical Treatment Protocol for Peripheral Nerve Dysfunction of the Lower Extremity: A Systematic Approach

Dysfunction of the tibial nerve can progress to painful and potentially disabling conditions. There are multiple sites of entrapment along the course of the tibial nerve. Detailed knowledge of the anatomy and anatomic variations is critical for a surgeon to be able to properly diagnose and treat patients with tibial nerve injuries. Repair of tibial nerve injuries involves a thorough history, physical examination, diagnostic studies, and microsurgical techniques. This article discusses sites of tibial nerve entrapment and use of a surgical algorithm that provides a systematic approach that has been successful within the literature in treating chronic tibial neuritic pain.

Hands-free Adjustment of the Microscope in Microneurosurgery

BACKGROUND

In microneurosurgery, the operating microscope plays a vital role. The classical neurosurgical operation is bimanual, that is, the microsurgical instruments are operated with both hands. Often, operations have to be carried out in narrow corridors at the depth of several centimeters. With current technology, the operator must manually adjust the field of view during surgery-which poses a disruption in the operating flow. Until now, technical adjuncts existed in the form of a mouthpiece to move the stereo camera unit or voice commands and foot pedals to control other interaction tasks like optical configuration. However, these have not been widely adopted due to usability issues. This study tests 2 novel hands-free interaction concepts based on head positioning and gaze tracking as an attempt to reduce the disruption during microneurosurgery and increase the efficiency of the user.

METHODS

Technical equipment included the Pentero 900 microscope (Carl Zeiss Microscopy GmbH, Jena, Germany), HTC Vive Pro (HTC, Taoyuan District (HQ), Taiwan), and an inbuilt 3D-printed target probe. Eleven neurosurgeons including 7 residents and 4 consultants participated in the study. The tasks created for this study were with the intention to mimic real microneurosurgical tasks to maintain applicative accuracy while testing the interaction concepts. The tasks involved visualization system adjustment to the specific target and touching the target. The first trial was conducted in a virtual reality setting applying the novel hands-free interaction concepts, and the second trial was conducted performing the same tasks on a 3D-printed target probe using manual field of view adjustment. The participants completed both trials with the same predetermined tasks, in order to validate the feasibility of the novel technology. The data collected for this study were obtained with the help of review protocols, detailed post-trial interviews, video and audio recordings, along with time measurements while performing the tasks.

RESULTS

The user study conducted at the Charité Hospital in Berlin found that the gaze-tracking and head-positioning- based microscope adjustment were 18% and 29% faster, respectively, than the classical bimanual adjustment of the microscope. Focused user interviews showed the users' proclivity for the new interaction concepts, as they offered minimal disruption between the simultaneous target selection and camera position adjustment.

CONCLUSIONS

The hands-free interaction concepts presented in this study demonstrated a more efficient execution of the microneurosurgical tasks than the classical manual microscope and were assessed to be more preferable by both residents and consultant neurosurgeons.

First-in-Man Clinical Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery

BACKGROUND

During its development and preclinical assessment, a novel, 3-dimensional (3D), high-definition (4K-HD) exoscope system was formerly shown to provide an immersive surgical experience, while maintaining a portable, low-profile design.

OBJECTIVE

To assess the clinical applicability of this 3D 4K-HD exoscope via first-in-man surgical use.

METHODS

The operative workflow, functionality, and visual haptics of the 3D 4K-HD exoscope were assessed in a variety of microneurosurgical cases at 2 US centers.

RESULTS

Nineteen microneurosurgical procedures in 18 patients were performed exclusively using the 3D 4K-HD exoscope. Pathologies treated included 4 aneurysms, 3 cavernous malformations (1 with intraoperative electrocorticography), 2 arteriovenous malformations, 1 foramen magnum meningioma, 1 convexity meningioma, 1 glioma, 1 occipital cyst, 1 chiari malformation, 1 carotid endarterectomy, 1 subdural hematoma, 1 anterior cervical discectomy and fusion, and 2 lumbar laminectomies. All patients experienced good surgical and clinical outcomes. Similar to preclinical assessments, the 3D 4K-HD exoscope provided an immersive 3D surgical experience for the primary surgeon, assistants, and trainees. The small exoscope frame, large depth of field, and hand/foot pedal controls improved exoscope mobility, decreased need to re-focus, and provided unobstructed operative corridors. Flexible positioning of the camera allows the surgeon's posture to be kept in a neutral position with uncompromised viewing angles.

CONCLUSION

The first-in-man clinical experience with the 3D 4K-HD exoscope confirms its excellent optics and ergonomics for the entire operative team, with high workflow adaptability for a variety of microneurosurgical cases. Expanded clinical use of the 3D 4K-HD exoscope is justified.

The Trigeminal Nerve Injury

Trigeminal nerve branches are never far from the operating field of the oral and maxillofacial surgeon. Increasingly the surgeon is required to provide accurate diagnosis and grading of trigeminal nerve injury, and surgical management by oral and maxillofacial surgeons will become common. Although trauma and ablative procedures for head and neck pathology can cause injuries, dentoalveolar surgical procedures remain an important cause of injury to the fifth cranial nerve, with the third division being the main branch affected. Oral and maxillofacial surgeons should be aware of strategies of avoiding iatrogenic injury, and know when referral and surgical management are appropriate.

First-Onset Hypokalemic Periodic Paralysis Following Surgery for Myxopapillary Ependymoma

BACKGROUND

Hypokalemic periodic paralysis is a rare skeletal muscle channelopathy characterized by intermittent episodes of acute flaccid paralysis with associated hypokalemia. We present here the case of a first-onset hypokalemic periodic paralysis triggered by lumbar spinal surgery for tumor resection.

CASE DESCRIPTION

A 37-year-old male without any known prior medical conditions presented with a first-onset attack of hypokalemic paralysis 1.5 days after lumbar spinal surgery for myxopapillary ependymoma. Initially, the patient presented paraparesis mimicking a spinal cord compression, and while en route for imaging there was an abrupt onset of flaccid paralysis with significant respiratory distress. The emergency blood tests revealed extreme hypokalemia with a serum potassium of 1.42 mm/L. The patient was transferred to the intensive care unit, intubated, sedated, and administered intravenous reperfusion with an infusion dose of 20 mEq/hour potassium in a solution of 5% mannitol. Following reperfusion, the patient recovered completely in 12 hours. Renal potassium hyperexcretion and hyperthyroidism were excluded by laboratory tests. The diagnosis was confirmed by genetic tests showing mutation of the CACNA1S gene.

CONCLUSIONS

To the best of our knowledge, this is the first described case with the first onset triggered by a neurosurgical intervention and the second case following any kind of surgery. Neurosurgeons should consider hypokalemic periodic paralysis when encountering a rapidly evolving tetraparesis, even in an apparently healthy patient.

Three-Dimensional Printed Ergonomically Improved Microforceps for Microneurosurgery

OBJECTIVE

The aim of this study was to develop and validate an ergonomically improved microforceps, which is a neurosurgical instrument used in microscopic procedures. The distance between tips of microforceps becomes large at high magnification of the operating microscope. This results in tips moving out of view and causes ergonomic discomfort.

METHODS

The design criteria for ergonomic microforceps were defined, which primarily involved a reduction in the distance between tips and applied force. Computer models of the existing and modified microforceps were created and fabricated using direct metal laser sintering. Ten neurosurgeons validated the developed instrument and provided feedback. In objective validation, video feed of the operating microscope was marked and analyzed by an expert neurosurgeon.

RESULTS

In subjective validation, most of the neurosurgeons endorsed the ergonomic improvements. The parameters, including microforceps tips moving out of view (P = 0.0005), suture holding attempts (P = 0.001), and needle holding attempts (P = 0.03), were found to be statistically improved (Mann-Whitney U test), whereas the average time taken to tie 1 knot was not statistically improved (P = 0.06). The ergonomic modification also resulted in a reduction of applied force by 47.5%.

CONCLUSIONS

Validation results show that the developed instrument provides several ergonomic benefits for the microsuturing task under high magnification of the operating microscope.

Midline and Paramedian Supracerebellar Infratentorial Approach to The Pineal Region: A Comparative Clinical Study in 112 Patients

OBJECTIVE

The midline supracerebellar infratentorial (SCIT) approach and its paramedian development are commonly used for dealing with pineal lesions. Comparative clinical studies are lacking, however. We aim to establish the better performance of the paramedian SCIT approach in terms of clinical safety in surgically treated pineal cysts and pineal region tumors. Procedural functionality and effectiveness have been also analyzed.

METHODS

A comparative analysis of clinical, radiologic, pathologic, and surgical features, and outcome was performed between 55 midline and 57 paramedian SCIT approaches that were exclusively performed in 112 patients (57 pineal cysts and 55 tumors of the pineal region) operated in sitting position by a single surgeon. Information was retrieved from hospital records and microsurgical videos.

RESULTS

The paramedian SCIT approach linked with fewer postoperative complications (odds ratio [OR]: 0.40) and fewer approach-related complications (OR: 0.28) than the midline SCIT approach. The SCIT paramedian approach was achieved in a shorter time, by a smaller bone flap, and with fewer complex procedural steps than the midline approach. The SCIT paramedian approach did not require the opening of the falx cerebelli, midline cerebellar retraction, section of the midline cerebellar draining veins, nor wide opening of the dura. Gross total resection, size of the lesion, microsurgical time for removal, histopathological diagnosis and postoperative outcome were statistically similar in both groups.

CONCLUSIONS

The SCIT approach represents a safer and more functional approach for the removal of cysts and tumors of the pineal region than the classic midline approach, while maintaining the same effectiveness.

Effect of duration from lingual nerve injury to undergoing microneurosurgery on improving sensory and taste functions: retrospective study

Background

The prognosis of recovery following microneurosurgery for injured lingual nerves varies among individual cases. This study aimed to investigate if recovery ratios of sensory and taste functions are improved by the microneurosurgery within 6 months after lingual nerve injury.

Methods

We retrospectively assessed 70 patients who underwent microneurosurgery at the Wakayama Medical University Hospital for lingual nerve injuries between July 2004 and December 2016. Sensory and taste functions in lingual nerves were preoperatively evaluated using a static two-point discrimination test, an intact superficial pain/tactile sensation test, and a taste discrimination test. They were evaluated again at 12 and at 24 months postoperatively. The abundance ratio of Schwann cells in the excised traumatic neuromas was analyzed with ImageJ software following immunohistochemistry with anti S-100β antibody.

Results

In early cases (microneurosurgery within 6 months after the injury), recovery ratios of sensory and taste functions were not significantly different at 24 months after microneurosurgery compared with later cases (microneurosurgery more than 6 months after the injury). Meanwhile, the ratio of patients with taste recovery within 12 months after microneurosurgery was significantly decreased in late cases compared with early cases. The abundance ratio of Schwann cells in traumatic neuroma was also significantly lower in later cases.

Conclusion

Microneurosurgery more than 6 months after lingual nerve injury did not lead to decreased recovery ratio of sensory and taste functions, but it did lead to prolonged recovery of taste. This delay may be associated with a decrease in the abundance ratio of Schwann cells in traumatic neuromas.

Systematic review of pineal cysts surgery in pediatric patients

INTRODUCTION

We present a consecutive case series and a systematic review of surgically treated pediatric PCs. We hypothesized that the symptomatic PC is a progressive disease with hydrocephalus at its last stage. We also propose that PC microsurgery is associated with better postoperative outcomes compared to other treatments.

METHODS

The systematic review was conducted in PubMed and Scopus. No clinical study on pediatric PC patients was available. We performed a comprehensive evaluation of the available individual patient data of 43 (22 case reports and 21 observational series) articles.

RESULTS

The review included 109 patients (72% females). Ten-year-old or younger patients harbored smaller PC sizes compared to older patients (p < 0.01). The pediatric PCs operated on appeared to represent a progressive disease, which started with unspecific symptoms with a mean cyst diameter of 14.5 mm, and progressed to visual impairment with a mean cyst diameter of 17.8 mm, and hydrocephalus with a mean cyst diameter of 23.5 mm in the final stages of disease (p < 0.001). Additionally, 96% of patients saw an improvement in their symptoms or became asymptomatic after surgery. PC microsurgery linked with superior gross total resection compared to endoscopic and stereotactic procedures (p < 0.001).

CONCLUSIONS

Surgically treated pediatric PCs appear to behave as a progressive disease, which starts with cyst diameters of approximately 15 mm and develops with acute or progressive hydrocephalus at the final stage. PC microneurosurgery appears to be associated with a more complete surgical resection compared to other procedures.

Extent of Resection and Long-Term Survival of Pineal Region Tumors in Helsinki Neurosurgery

BACKGROUND

Pineal region tumors represent challenging surgical lesions with wide ranges of survival reported in different surgical series. In this article, we emphasize the role of complete microsurgical resection (CMR) to obtain a favorable long-term outcome of pineal region tumors.

METHODS

We report a retrospective study of pineal region tumors operated on in Helsinki Neurosurgery between 1997 and 2015. Information was obtained from the hospital records, and an evaluation of the Finnish population register was conducted in July 2018 to determine the current status of the patients.

RESULTS

A total of 76 pineal region tumors were operated on. The survival was 62% at a mean follow-up of 125 ± 105 months (range, 0-588 months), and the disease-related mortality was limited to 14 patients (18.4%). Up to July 2018, 29 patients had died. Two patients died 1 and 3 months after surgery of delayed thalamic infarctions, 12 patients of disease progression, and 15 had non-disease-related deaths. Only 1 patient was lost in the long-term follow-up. Ten of 14 disease-related deaths occurred during the first 5 years of follow-up: 5 diffuse gliomas, 3 germ cell tumors, 1 grade II-III pineal parenchymal tumor of intermediate differentiation, and 1 meningioma. CMR was linked to better tumor-free survival and long-term survival, with the exception of diffuse gliomas.

CONCLUSIONS

CMR, in the setting of a multidisciplinary management of pineal region tumors, correlates with favorable survival and with minimal mortality. Surgically treated grade II-IV gliomas constitute a particular group with high mortality within the first 5 years independently of the microsurgical resection.

Innovations in the Art of Microneurosurgery for Reaching Deep-Seated Cerebral Lesions

Deep-seated cerebral lesions have fascinated and frustrated countless surgical innovators since the dawn of the microneurosurgical era. To determine the optimal approach, the microneurosurgeon must take into account the characteristics and location of the pathological lesion as well as the operator's range of technical expertise. Increasingly, microneurosurgeons must select between multiple operative corridors that can provide access to the surgical target. Innovative trajectories have emerged for many indications that provide more flexible operative angles and superior exposure but result in longer working distances and more technically demanding maneuvers. In this article, we highlight 4 innovative surgical corridors and compare their strengths and weaknesses against those of more conventional approaches. Our goal is to use these examples to illustrate the following principles of microneurosurgical innovation: (1) discover more efficient and flexible exposures with superior working angles; (2) ensure maximal early protection of critical neurovascular structures; and (3) effectively handle target pathology with minimal disruption of normal tissues.

Ossification of the roof of the porus trigeminus with duplicated abducens nerve

Ossification of parts of the intracranial dura mater is common and is generally accepted as an age-related finding. Additionally, duplication of the abducens nerve along its course to the lateral rectus muscle is a known, although uncommon anatomical variant. During routine cadaveric dissection, an ossified portion of dura mater traveling over the trigeminal nerve's entrance (porus trigeminus) into the middle cranial fossa was observed unilaterally. Ipsilaterally, a duplicated abducens nerve was also observed, with a unique foramen superolateral to the entrance of Dorello's canal. To our knowledge, there has been no existing report of a simultaneous ossified roof of the porus trigeminus with an ipsilateral duplicated abducens nerve. Herein, we discuss this case and the potential clinical and surgical applications. We believe this case report will be informative for the skull base surgeon in the diagnosis of neuralgic pain in the frontomaxillary, andibular, orbital, and external and middle ear regions.

The microsurgical management of benign pineal cysts: Helsinki experience in 60 cases

Background:

Microsurgical resection represents a well-accepted management option for symptomatic benign pineal cysts. Symptoms such as a headache, hydrocephalus, and visual deficiency are typically associated with pineal cysts. However, more recent studies reported over the past years have characterized additional symptoms as a part of the clinical manifestation of this disease and represent additional indications for intervention.

Methods:

We present a retrospective review of patients with histologically confirmed benign pineal cysts that were operated on in our department between 1997 and 2015. A demographic analysis, evaluation of preoperative status, surgical treatment, as well as immediate and long-term clinical and radiological outcomes were conducted.

Results:

A total of 60 patients with benign pineal cysts underwent surgery between 1997 and 2015. Gross total resection was achieved in 58 cases. All patients except one improved in their clinical status or had made a full recovery at the time of the last follow-up. The key steps for surgical resection of pineal cysts are reported, based on an analysis of representative surgical videos.

Conclusions:

We describe in this paper one of the largest series of microsurgically treated pineal cysts. In our opinion, judicious microsurgery remains the most suitable technique to effectively deal with this disease.

The Microneurosurgical Training Model for Intrinsic and Extrinsic Brain Tumor Surgery Using Polyurethane Foam and Fresh Cadaveric Cow Brain: An Experimental Study

Objective

To evaluate the feasibility of an experimentally designed brain tumor model consisting of polyurethane foam and fresh cadaveric cow brain for the surgical training of the technique for tumor ablation.

Methods

A laboratory-training model was created for microneurosurgical intervention of intrinsic brain tumor ablation covering microdissection of the brain tissue and opening of the pia mater, dissection and separation of the sulcal and cisternal structures, and dissection and removal of the tumor tissue. The left front parietal lobe was used as the area of interest for this experimental study. One-centimeter cube polyurethane foam was injected 2-cm deep inside the brain tissue using a plastic injection tube. After 5 minutes, the model was ready to use under the operating microscope for dissection, separation, and removal of the tumor tissue. The compatibility of the training model also was evaluated as poor, acceptable, and perfect.

Results

Ten stripped fresh cadaveric cow brains were used in this experimental feasibility study. The compatibility of the model was evaluated as poor, acceptable, and perfect in 1, 6, and 3 subjects, respectively.

Conclusions

In intrinsic brain tumor ablation, surgical manipulations of sulcal, cisternal, and fissural dissection must be undertaken while preserving vital neural and vascular structures. We believe that our model holds promise in developing the technical skills of neurosurgeons in training.

Microvascular Fluorescence in Spinal Cord Repair

The release of the placode and reconstruction of the myelomeningocele, preserving the maximum neural tissue is a challenge for the neurosurgeon. Vascular fluorescence with indocyanine green and/or fluorescein allows observation of the microvascularization of the spinal cord and adequately identifies viable tissue.

Comparison of Subjective and Objective Assessments of Neurosensory Function after Lingual Nerve Repair

OBJECTIVE

Mandibular third molar extractions are important in oral maxillofacial surgery. Damage to the lingual nerves, although rare, is a possible complication. There are reports of postoperative recovery after lingual nerve repair, but few reports have compared subjective and objective assessments of neurosensory function. Therefore, this study aims to compare subjective and objective assessments of neurosensory function after lingual nerve repair.

SUBJECTS AND METHODS

This retrospective cohort study comprised 52 patients with lingual nerve anesthesia after third molar extraction at the Department of Oral and Maxillofacial Surgery, Wakayama Medical University Hospital, Wakayama, Japan, between December 2008 and December 2015. We recorded pre- and postoperative (6 months and 12 months) neurosensory examinations.

RESULTS

Patient's subjective assessments of neurosensory function suggested improvement between the preoperative period and 12 months postoperation, although this difference was not significant. Objective assessment based on examination and testing, on the other hand, showed a significant difference in improvement (p < 0.05).

CONCLUSIONS

There was no evidence that improvement of subjective preoperative and postoperative assessments was significantly associated with improvement of objective neurosensory assessments after lingual nerve repair. Overall physical condition and background were thought to affect subjective evaluation. Subjective assessment is important in conjunction with objective evaluation because it may reveal dysesthesia that would otherwise be missed. In the future, we will examine those cases in whom subjective assessments showed no improvement although objective assessments showed improvement.

Pineal Parenchymal Tumors of Intermediate Differentiation: A long-Term Follow-Up Study in Helsinki Neurosurgery

BACKGROUND

Pineal parenchymal tumors of intermediate differentiation (PPTIDs) are rare lesions with particular features compared with other pineal parenchymal tumors.

METHODS

We present a retrospective review of patients with histologically confirmed PPTIDs who were operated on in our department between 1997 and 2015. A demographic analysis and an evaluation of preoperative status, surgical treatment, as well as immediate and long-term clinical and radiologic outcomes were conducted.

RESULTS

Fifteen patients with PPTIDs were operated on between 1997 and 2015. Gross total removal was achieved in 11 cases; 2 patients underwent near-total resection, 1 partial resection, and 1 received brachytherapy after an endoscopic biopsy. Nine patients required external radiation therapy (4 due to a pleomorphic histology of their lesion including pineoblastoma features in 3 of them; 3 after a subtotal resection; and 2 for tumor recurrence). No patient received chemotherapy. The survival rate of our patients was 57.1% at a mean follow-up of 137.2 ± 77.6 months (39-248 months).

CONCLUSIONS

A proper multidisciplinary management of PPTIDs based on a gross total removal of the lesion, and an adjuvant radiotherapy in selected cases, may improve the overall survival of these aggressive tumors.

Pros and cons of using ORBEYE™ for microneurosurgery

OBJECTIVE

To evaluate the pros and cons of using a newly developed microscope, ORBEYE™, during microneurosurgery.

PATIENTS AND METHODS

ORBEYE™ use in 14 microneurosurgical procedures was retrospectively assessed by nine neurosurgeons after the procedure. A questionnaire comprising 20 questions was designed and used for evaluation.

RESULTS

Compared with the current gold standard, the binocular microscope, ease of setting up the equipment was scored the highest, whereas ease of conducting surgery in a position of an assistant was scored the lowest. Among characteristics of ORBEYE™ itself, the space-saving feature was scored the highest and was followed by the ability to perform procedures in a comfortable position. The only characteristic that was rated below average was ease of operation in a position of an assistant. Neurosurgeons with greater experience (more than five procedures using ORBEYE™) provided significantly higher scores (p = 0.0196) for characteristics of ORBEYE™ itself compared with neurosurgeon with fewer ORBEYE™ experience.

CONCLUSIONS

The main benefits of the ORBEYE^TM are its compact size and freedom from focusing through the eye lens of a conventional binocular microscope. However, it appears to be disadvantageous for operating in a position of an assistant because the surgical field has a rotated view on the monitor from a position of an assistant. Nonetheless, because of certain advantages, we believe the ORBEYE™ could be of additional help to use of conventional binocular microscope at the moment and will facilitate microneurosurgery in the future.

[Dynamic retraction microneurosurgery for the treatment of medial tentorial meningiomas]

Objective: To investigate the effectiveness and clinical significance of dynamic retraction microneurosurgery for the treatment of medial tentorial meningiomas. Methods: From January 2011 to December 2016, a cohort of 28 patients with medial tentorial meningiomas were treated by microneurosurgery at the First Affiliated Hospital of Chongqing Medical University. Patients who treated intraoperatively with dynamic retraction surgery from January 2014 to December 2016 were assigned into dynamic retraction group, and those with fixed retractors intraoperatively from January 2011 to December 2013 were assigned into retractor group. The surgical approaches tailored in our patients were based on predominant direction of tumor extension. The extent of tumor resection was scored according to the Simpson's classification scale. Comparisons of tumor size, operation time, hospitalization time, retraction-related injury, tumor Simpson resection grade and Karnofsky Performance Scale(KPS) score six months after surgery were also made between two groups. Results: A total of 12 patients(retractor group) were treated with the use of self-retaining brain retractors intraoperatively and dynamic retraction surgical procedure was performed intraoperatively in 16 patients(dynamic retraction group). The difference between two groups with regard to sex, age, tumor size, operation time and tumor Simpson resection grade was not statistically significant(all P>0.05). The mean duration of hospital time was shorter in the dynamic retraction group than that in the retractor group(18.3 d±1.8 d vs 20.2 d±1.3 d, P=0.004). The dynamic retraction group had lower incidence of retraction-related injury compared with the retractor group(1/16 vs 6/12), P=0.022]. The dynamic retraction group had better neurological recovery rate with KPS >80 evaluated six months after surgery compared with the retractor group(14/16 vs 5/12, P=0.017). Conclusions: Dynamic retraction microneurosurgery for the treatment of medial tentorial meningiomas is feasible, which can obviate or reduce the amount of brain retraction needed, and may be of help in lowering the risk of postoperative neurological deficits and complications and leading to reduced hospitalization cost and improved surgical outcomes.

Praying Sitting Position for Pineal Region Surgery: An Efficient Variant of a Classic Position in Neurosurgery

BACKGROUND

The sitting position has lost favor among neurosurgeons partly owing to assumptions of increased complications, such as venous air embolisms and hemodynamic disturbances. Moreover, the surgeon must assume a tiring posture. We describe our protocol for the "praying position" for pineal region surgery; this variant may reduce some of the risks of the sitting position, while providing a more ergonomic surgical position.

METHODS

A retrospective review of 56 pineal lesions operated on using the praying position between January 2008 and October 2015 was performed. The praying position is a steeper sitting position with the upper torso and the head bent forward and downward. The patient's head is tilted about 30° making the tentorium almost horizontal, thus providing a good viewing angle. G-suit trousers or elastic bandages around the lower extremities are always used.

RESULTS

Complete lesion removal was achieved in 52 cases; subtotal removal was achieved in 4. Venous air embolism associated with persistent hemodynamic changes was nonexistent in this series. When venous air embolism was suspected, an immediate reaction based on good teamwork was imperative. No cervical spine cord injury or peripheral nerve damage was reported. The microsurgical time was <45 minutes in most of the cases. Postoperative pneumocephalus was detected in all patients, but no case required surgical treatment.

CONCLUSIONS

A protocolized praying position that includes proper teamwork management may provide a simple, fast, and safe approach for proper placement of the patient for pineal region surgery.

Frugal Malleable Microdissectors and Arachnoid Knives for Microneurosurgery

BACKGROUND

Similar to most of the other medical and surgical fields, neurosurgery has changed drastically in recent decades, especially in instrumentation and equipment. Safety, scope of treating initially considered nontreatable neurosurgical conditions, and prognosis of most neurosurgical procedures have improved significantly. Newer instruments and equipments are being introduced exponentially, leading to tremendous cost escalation of neurosurgical treatment. However, equitable distribution of neurosurgical services in society is far from reality. We need to look back and learn from our teachers and forefathers of neurosurgery their innovative ways to accomplish difficult procedures without advanced tools and techniques. Microneurosurgery is considered a highly skilled technique, and instruments used for it are delicate, precise, and costlier than similar instruments for macroneurosurgery.

TECHNIQUE AND CONCLUSION

Frugal innovative techniques and tools are presented for making stainless steel wire and plate microdissectors that are effective for microneurosurgical procedures and can be helpful for neurosurgeons working in resource-poor settings.

Modified Extradural Temporopolar Approach for Paraclinoid Aneurysms: Operative Nuance and Surgical Result

BACKGROUND

Extradural temporopolar approach can provide extensive exposure of the anterior clinoid process, which can prevent intraoperative neurovascular injury in anterior clinoidectomy for paraclinoid aneurysms. The present study investigates the usefulness of this modified technique, and operative nuances are discussed here.

METHODS

We retrospectively reviewed the medical charts of 30 consecutive patients with paraclinoid aneurysms who underwent treatment with this modified extradural temporopolar approach between September 2009 and March 2016.

RESULTS

Worsening of visual acuity was documented postoperatively in three patients (10.0%), and visual field function worsened in three patients (10.0%). Postoperative outcome was good recovery in all patients. No operation-related mortality occurred in the series.

CONCLUSION

Extradural anterior clinoidectomy via the modified extradural temporopolar approach is safe and may be recommended for surgical treatment of paraclinoid aneurysms to reduce the risk of intraoperative optic neurovascular injury.

Affordable self-regulating irrigation device for microsurgery using readily available malleable wire and a Silastic tube: a technical note

BACKGROUND

A relevant irrigating and flushing maneuver during cerebral microsurgical procedures allows for a neat and optimal operative field. However, when operating on the deep region of the brain, a delicately created slim surgical corridor could unintentionally hinder the assisting surgeon from properly performing this routine maneuver.

METHOD

To address this problem, the authors devised a useful and convenient irrigation system that can be used during cerebral microsurgery.

RESULTS

This system only necessitates a readily available silastic feeding tube and a malleable wire. The advantages of our devised system include the convenience of free molding, good endurance of the molded contour, and easy control over the amount of irrigation.

CONCLUSIONS

In this report, the authors demonstrated technical tips for using this newly devised system.

Flexible Ultrathin Endoscope Integrated with Irrigation Suction Apparatus for Assisting Microneurosurgery

BACKGROUND

Endoscopy can observe the anatomical components in a deeply located and/or hidden area during neurosurgical procedures under the operating microscope. We have newly developed a flexible ultrathin endoscope integrated with irrigation suction apparatus (FUEISA) to visualize deeply located and/or hidden areas for assisting microneurosurgery.

OBJECTIVE

The present study investigated the usefulness of the FUEISA system for direct clipping surgery of cerebral aneurysms.

METHODS

Twenty-one patients underwent microneurosurgery assisted with the FUEISA system for direct clipping of cerebral aneurysms. The flexible ultrathin endoscope (outer diameter 0.75mm) consists of an image guide (6000 dpi) and a light guide, integrated with the irrigation suction apparatus. This endoscopic system was inserted before and after clipping to observe the anatomical conditions surrounding the lesions.

RESULTS

In all cases, handling and operation of the FUEISA was technically successful during the surgical procedure. The ultrathin endoscope was adequately integrated with the irrigation suction apparatus in all cases. General anatomy visualization including the lenticulostriate arteries, medial striate arteries, and/or internal carotid artery perforators was possible, and the correct clip positioning and vessel conditions were easily checked. The endoscope revealed that the clip had been positioned incorrectly in one case. No complications associated with the endoscopic system occurred.

CONCLUSIONS

The FUEISA system can be applied with safe manipulation, which was remarkably useful for confirmation of the presence of perforators and cranial nerves behind the lesions, particularly anatomical components located in deep and/or hidden areas during clipping of cerebral aneurysms.

Moyamoya Disease in an 8-Year-Old Boy: Direct Bypass Surgery in a Province of Peru

BACKGROUND

Pediatric moyamoya cases may be very arduous, even more so in a developing country, where access to specialized centers may be prevented by different factors.

CASE DESCRIPTION

Herein we report a challenging case, which was managed in the new Neurosurgical Center of Trujillo, regarding the direct anastomosis between the left superficial temporal artery and a cortical branch of the left middle cerebral artery in a 8-year-old Peruvian boy with moyamoya disease. Postoperatively, the patient's motor deficits and aphasia improved. To the best of our knowledge, this is the first performance of a direct revascularization for a pediatric moyamoya case in Peru.

CONCLUSIONS

The creation of highly specialized neurosurgical centers in the main strategic places of developing countries may allow optimal treatment of neurosurgical patients with complex diseases.

"Dirty coagulation" technique as an alternative to microclips for control of bleeding from deep feeders during brain arteriovenous malformation surgery

BACKGROUND

Meticulous haemostasis is one of the most important factors during microneurosurgical resection of brain arteriovenous malformation (AVM). Controlling major arterial feeders and draining veins with clips and bipolar coagulation are well-established techniques, while managing with bleeding from deep tiny vessels still proves to be challenging. This technical note describes a technique used by the senior author in AVM surgery for last 20 years in dealing with the issue highlighted.

METHOD

"Dirty coagulation" is a technique of bipolar coagulation of small feeders carried out together with a thin layer of brain tissue that surrounds these fragile vessels. The senior author uses this technique for achieving permanent haemostasis predominantly in large and/or deep-seated AVMs. To illustrate the efficacy of this technique, we retrospectively reviewed the outcome of Spetzler-Martin (SM) grade III-V AVMs resected by the senior author over the last 5 years (2010-2015).

RESULTS

Thirty-five cases of AVM surgeries (14 SM grade III, 15 SM grade IV and 6 SM grade V) in this 5-year period were analysed. No postoperative intracranial haemorrhage was encountered as a result of bleeding from the deep feeders. Postoperative angiograms showed complete resection of all AVMs, except in two cases (SM grade V and grade III).

CONCLUSIONS

"Dirty coagulation" provides an effective way to secure haemostasis from deep tiny feeders. This cost-effective method could be successfully used for achieving permanent haemostasis and thereby decreasing postoperative haemorrhage in AVM surgery.

Two surgeons four-hand microneurosurgery with universal holder system: technical note

A new technique for collaborative performance of complex skull base and cerebrovascular procedures is described. The benefits of this approach for patient safety and surgical education are discussed.

Microsurgical resection of tumors of the lateral and third ventricles: operative corridors for difficult-to-reach lesions

Tumors of the lateral and third ventricles are cradled on all sides by vital vascular and eloquent neural structures. Microsurgical resection, which always requires attentive planning, plays a critical role in the contemporary management of these lesions. This article provides an overview of the open microsurgical approaches to the region highlighting key clinical perspectives.

Intracranial Vertebral Artery Aneurysms: Clinical Features and Outcome of 190 Patients

BACKGROUND

Vertebral artery (VA) aneurysms comprise approximately one-third of posterior circulation aneurysms. They are morphologically variable, and located critically close to the cranial nerves and the brainstem. We aim to represent the characteristics of these aneurysms and their treatment, and to analyze the outcome.

METHODS

We reviewed retrospectively 9709 patients with intracranial aneurysms. Of these, we included 190 with aneurysms at the VA or VA-posterior inferior cerebellar artery junction. These patients were treated in the Department of Neurosurgery, Helsinki, Finland, between 1934 and 2011.

RESULTS

The 190 patients had 193 VA aneurysms, among which 131 (68%) were ruptured. The VA aneurysm caused a mass effect in 7 and ischemia in 2 patients. Compared to 4387 patients with a ruptured aneurysm in other locations, those with a VA aneurysm were older, their aneurysms were more often fusiform, and more often caused intraventricular hemorrhages. Among surgically treated aneurysms, clipping was the treatment in 91 (88%) saccular and 11 (50%) fusiform aneurysms. Treatment was endovascular in 13 (9%), and multimodal in 6 (4%) aneurysms. Within a year after aneurysm diagnosis, 53 (28%) patients died. Among the survivors, 104 (93%) returned to an independent or to their previous state of life; only 2 (2%) were unable to return home.

CONCLUSIONS

Microsurgery is a feasible treatment for VA aneurysms, although cranial nerve deficits are more common than in endovascular surgery. Despite the challenge of an often severe hemorrhage, of challenging morphology, and risk for laryngeal palsy, most patients surviving the initial stage return to normalcy.

The value of intraoperative neurophysiological monitoring for microsurgical removal of conus medullaris lipomas: a 12-year retrospective cohort study

Background

Lipomas in the lower spinal canal can lead to progressive neurological deficits, so they may have to be surgically removed. Intraoperative neurophysiological monitoring serves to minimize the morbidity of the surgical procedure. However, so far there are no evidence-based recommendations which type of monitoring procedure or combination of procedures to choose.

Methods

The aim of this study was to evaluate the feasibility and value of various intraoperative monitoring techniques: motor and sensory evoked potentials (MEP, SEP), free-running and triggered electromyography (EMG). Thirty cases of spinal lipomas of the Conus medullaris (dorsal Type A: 20.0%; caudal Type B: 33.3%; transitional Type C: 46.7%) were retrospectively evaluated over a 12-year period.

Results

The patients were mostly pediatric and suffered from persistent pain (73.3%), pareses (56.7%), sensory deficits (43.4%), and/or urogenital dysfunctions (60.0%). SEPs were successfully evoked in 66.7% of cases, MEPs in 86.7% of cases, and EMGs in 100%. MEP alterations correlated with direct mechanical maneuvers in the operating site. SEP changes correlated mostly with physiological events, such as rinsing/cooling of the operating site. Spike-, burst- or tonic train-activity was found in the free-running EMG that occurred only with certain manipulation patterns. Irreversible MEP changes and signal loss in the triggered EMG correlated with post-operative deficits.

Conclusions

The results of this study showed, that intraoperative monitoring could be considered a helpful tool during lipoma tumor surgery near the Conus medullaris. Most reliable results were obtained from transcranial MEPs, free-running EMGs, and triggered EMGs. That’s why the authors favor a routine set-up consisting of at least these three techniques, as this enables mapping at the beginning of the operation, continuous functional testing during surgery, and prognosis of the post-operative symptomology.

Microsurgical training model for residents to approach to the orbit and the optic nerve in fresh cadaveric sheep cranium

Background:

Neurosurgery and ophthalmology residents need many years to improve microsurgical skills. Laboratory training models are very important for developing surgical skills before clinical application of microsurgery. A simple simulation model is needed for residents to learn how to handle microsurgical instruments and to perform safe dissection of intracranial or intraorbital nerves, vessels, and other structures.

Materials and Methods:

The simulation material consists of a one-year-old fresh cadaveric sheep cranium. Two parts (Part 1 and Part 2) were designed to approach structures of the orbit. Part 1 consisted of a 2-step approach to dissect intraorbital structures, and Part 2 consisted of a 3-step approach to dissect the optic nerve intracranially.

Results:

The model simulates standard microsurgical techniques using a variety of approaches to structures in and around the orbit and the optic nerve.

Conclusions:

This laboratory training model enables trainees to gain experience with an operating microscope, microsurgical instruments and orbital structures.

Off-the-job microsurgical training on dry models: Siberian experience

BACKGROUND

Microsurgical training has become an obligatory part of many neurosurgical training programs.

OBJECTIVE

To assess the cost and effectiveness of acquiring and maintaining microneurosurgical skills by training on an off-the-job basis using dry models.

METHODS

A dry off-the-job microneurosurgical training module was set up. Training exercises involved microdissection in a deep operation field, suturing and tying on gauze, untying, pushing of thread end, and microanastomosis. The time to complete the task and success rate were evaluated. The total cost of all necessary equipment and expendables for the training module was US$910.

RESULTS

Fifteen residents participated in the continuous off-the-job training. The average time taken to perform the anastomosis decreased after the month of training from 90 to 20 minutes. Authors revealed that at 2 months, the total time and time to complete anastomosis increased significantly for the participants who discontinued practice after the first month, compared with those who just practiced suturing on gauze after the first month (P < 0.01). The average Northwestern Objective Microanastomosis Assessment Tool score was 36 for novice and 65 for experienced participants.

CONCLUSION

The dry off-the-job training showed to be readily available and can be helpful for microsurgical training in the low-income regions of the world. Our data suggest that microsurgical training should be continuous and repetitive. Simulation training may benefit from models for repetitive training of relevant technical part-skills.